In the US, the US Geological Survey has plenty of APIs. Here's a starter page with information: https://help.waterdata.usgs.gov/faq/automated-retrievals https:

In the US, the US Geological Survey has plenty of APIs. Here's a starter page with information: https://help.waterdata.usgs.gov/faq/automated-retrievals https://help.waterdata.usgs.gov/faq/automated-retrievals